The invention relates to a catheter or cannula system that facilitates cardiopulmonary surgeries and enables prolonged circulatory support of the heart. More specifically, the invention relates to an aortic catheter for segmenting and selectively perfusing the aorta during cardiopulmonary bypass.
Heart surgery has generally required major open chest surgical procedures that put the patient at risk. Relatively high mortality rates and complications result from such invasive surgeries. Further, the surgeries require extensive hospitalization and recuperation time. Surgical methods to correct heart problems are desirable which do not require open chest approaches. Some surgical techniques have been described for particular applications employing an intra-aortic catheter introduced into the vascular system of the patient.
Recent advances in the field of minimally invasive cardiac surgery have included the development of aortic catheters and methods for inducing cardioplegic arrest without the necessity of opening the patient""s chest with a stemotomy or other major thoracotomy. For example, U.S. Pat. No. Re 35,352 to Peters describes a single-balloon catheter for occluding a patient""s ascending aorta and a method for inducing cardioplegic arrest. A perfusion lumen or a contralateral arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. U.S. Pat. No. 5,584,803 to Stevens et al. describes a single balloon catheter for inducing cardioplegic arrest and a system for providing cardiopulmonary support during closed chest cardiac surgery. A coaxial arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. The occlusion balloon of these catheters must be very carefully placed in the ascending aorta between the coronary arteries and the arch vessels, therefore the position of the catheter must be continuously monitored to avoid complications.
One difficulty encountered with prior art aortic catheters is the tendency of the single balloon catheters to migrate or drift in the direction of the pressure gradient within the aorta. Specifically, during infusion of cardioplegia, the balloon catheter will tend to drift downstream away from the heart and toward the aortic arch and, when the cardiopulmonary bypass pump is engaged during the procedure, the balloon catheter will tend to drift upstream in the opposite direction toward the heart into the aortic root. This migration can be problematic if the balloon drifts downstream far enough to occlude one or more of the arch vessels, or upstream enough to occlude the coronary arteries, or to pass through the aortic valve into the ventricle.
PCT patent application WO 9721462 by Fan et al. attempts to overcome this problem with a balloon catheter having high friction areas on the outer surface of the balloon. A problem with this single balloon approach is that a relatively large balloon is needed to create enough friction to avoid migration of the inflated balloon. The larger the balloon is, the more carefully it must be placed in the ascending aorta to avoid occluding the coronary arteries or the arch vessels and the less margin of error there is should any balloon migration occur.
Furthermore, what is needed are medical instruments and cannula/catheters for compartmentalizing and selectively perfusing the cerebral circulation with antegrade flow. Such mechanisms are necessary to minimize complications of a vast array that are related to proper management of blood flow in the body. Selective perfusion can be used to prioritize the flow of oxygenated blood or other protective fluids to the various organ systems, therefore achieving optimal preservation of all organ systems within the body.
Furthermore, what is needed is a peripheral access catheter configuration that is more resistant than prior apparatus to migration due to pressure gradients within the patient""s aorta.
The following patents, and all other patents referred to herein, are hereby incorporated by reference in their entirety: U.S. Pat. Nos. 5,308,320, 5,383,854, 582,093 and 5,906,588 by Safar et al.; U.S. patent application Ser. No. 08/909,293, filed Aug. 11, 1997, by Safar et al.; U.S. patent application Ser. No. 09/152,589, filed Sep. 11, 1998, by Safar et al.; U.S. Pat. No. 5,738,649, by John A. Macoviak; U.S. patent application Ser. No. 09/060,412 filed Apr. 14, 1998 by Macoviak; U.S. Pat. Nos. 5,833,671, 5,827,237 by John A. Macoviak and Michael Ross; U.S. patent application Ser. No. 08/665,635, filed Jun. 17, 1996, by John A. Macoviak and Michael Ross; and U.S. patent application Ser. No. 09/205,753, filed Dec. 8, 1998, by Bresnahan et al.
Accordingly, the invention provides a catheter or cannula having a flow control member positioned near the distal end of the catheter for occluding a first body lumen at a point where a second body lumen branches from the first lumen, and for perfusing the branch lumen. The invention will be described more specifically herein relating to an aortic catheter or cannula having an occlusion member positioned in the aortic arch, having a length sufficient to cover the ostia of the arch vessels. The flow control member is intended to fulfill at least one and preferably all four of the following functions: (1) occluding the aorta at the aortic arch, (2) selectively perfusing one or more of the coronary arteries, the arch vessels, or the descending aorta with a selected fluid, (3) providing filtered perfusion to one or more of the coronary arteries, the arch vessels, or the descending aorta, and (4) resisting migration of the distal flow control member and the cannula.
The primary flow control member may be formed in a variety of configurations, but will include a primary flow control member positioned in the aortic lumen, having a length sufficient to cover the ostia of the arch vessels. The flow control member may comprise one or more inflatable balloons or one or more selectively deployable external catheter valves, or a combination of balloons and valves. In embodiments where the primary flow control member is a single inflatable balloon, the flow control member will have at least one permeable or mesh portion. The balloons used, whether porous or nonporous, may be elastic so that they stretch in proportion to the inflation pressure, or may be flaccid or sack-like so that they inflate at low pressure and reach their design diameter quickly. The sack-like balloons may be relatively non-compliant at their design diameter or they may be compliant, exhibiting elastic behavior after initial inflation, e.g. to closely fit the aortic lumen size and curvature.
The catheter may further include one or more auxiliary flow control members located upstream or downstream from the primary flow control member to further segment the patient""s circulatory system for selective perfusion to different organ systems or to assist in anchoring the catheter in a desired position. Usable auxiliary flow control members include, but are not limited to, expandable or inflatable members such as inflatable balloons and valves. Examples of various valves may include collapsible/expandable valves including retrograde valves, antegrade valves, and various central flow and peripheral flow valves. In addition, a combination of valves and inflatable members may be used as appropriate for a given procedure. In some embodiments, the catheter body can include one or more antegrade and retrograde valves, as well as one or more inflatable balloons. Inflatable balloons and collapsible/deployable valves have been previously incorporated by reference herein and any desirable or practical inflatable balloon or deployable valve may be used. Inflatable balloons typically include an interior chamber that is in fluid communication with an inflation lumen extending within the catheter shaft from a location from within the respective flow control member to a location in the proximal portion, which is adapted to extend out of the patient.
Preferably, the flow control member, and any auxiliary flow control members, or anchoring members, if present, are mounted on an elongated catheter shaft. In a preferred embodiment, the catheter shaft includes at least one lumen for inflating or otherwise deploying the primary flow control member and for perfusion of the arch vessels with oxygenated blood or other fluids, a lumen for corporeal perfusion, and a guidewire lumen. In alternate embodiments, lumens may be included for deploying the auxiliary flow control members, and for measuring the pressure at desired locations within the aorta. The catheter may be configured for retrograde deployment via a peripheral artery, such as the femoral artery, or it may be configured for antegrade deployment via an aortotomy incision or direct puncture in the ascending aorta.
In some embodiments of the invention, filtration may be an important feature. To capture embolic material without unduly disrupting blood flow, the porous section or sections must have an appropriate combination of characteristics including effective filter surface area and pore size; the correct combination depending on a number of factors including fluid pressure. For filters comprised of a mesh, the thread diameter is another important characteristic to consider. Typically, the flow rates required in the arch vessels total between 0.5 and 1.5 L/min depending on a variety of factors including the size of the patient and the temperature of the perfusate. Pore size is preferably 500 xcexcm or less, more preferably 200 xcexcm or less, and most preferably 50 xcexcm or less, but larger than at least a red blood cell, although larger pore sizes may be required in some embodiments.
Methods according to the present invention are described using the aortic catheter for occluding and compartmentalizing or partitioning the patient""s aortic lumen and for performing selective filtered aortic perfusion.